You might try a CMS or three to see if you like a package deal, rather than piecing together your own coded html with standalone items like the forums. The best feature is you log in once and it effects permissions for the entire site, rather than each piece requiring it's own db with registration and login.
I prefer e107, mainly because I've used it for so long and can get IRC help from the dev team. I have worked with phpNuke and postNuke, but wasn't fond of the admin area and found it harder to skin a theme. That's actually my pride is the theming.
You can check out my clan's
site to see some e107 options and there are user created plugins for nearly everything imaginable. Same goes for the other CMS's I suppose, but I had trouble finding the plugins since it's open source and there seems to be many variants.
Here's some of the links for that corperate project I worked on last fall. Still waiting for them to provide me the media to finish it all.
Original Site Check the Cabins link and Woods n Water links to see the originals of those.
Main Site Check The Ridge in the Development section for a really cool interactive map I did.
Woods n Water This is a sub-site. You can see the basic theme I did, with some minor variations between them and alternate coloring. The Cabins site replacement isn't live yet since there is some legal issue or something about what they can show, since they built some of them and they don't own them, I don't know. It's basically shades of green and such.
I would love to help you setup a test site to see the features of e107 and if you like, I'll develop a custom theme in exchange for you keeping me in mind for future work, should you need a hand. I'd love to do this stuff for a living. I couldn't believe when my contact drew up the billing for the work so far. I've made $1100 already. You believe companies pay that coin?!?